Mitochondrial (mt)DNA contains genes for 2 rRNAs, a set of tRNAs, and a number of mRNAs (in the range of 10). The genes for rRNAs and tRNAs have been mapped previously in our group. Our latest project has been the mapping of the mRNA genes. We have characterized 10 major nonribosomal transcripts of mtDNA and mapped their coding regions. Nine out of these 10 RNAs map in nonoverlapping positions and all are transcribed from uninterrupted genes.